This invention relates to bearings for roller conveyors.
Typically, roller conveyors have plural rollers aligned on parallel axes tranverse to a direction of conveyor flow. Hexagonal bars extend through the hollow tubular rollers and are fixed in hexagonal openings in parallel side frames. The rollers have bearings at each end. Outer races of the bearings hold the outer ends of the tubular rollers, and inner races of the bearings receive the hexagonal bars.
Historically axial ends of the tubular rollers are mechanically connected to outer casings or races of the bearings. One prior art method of mechanically connecting the bearings to the tubular rollers involves the insertion of the bearing within each end of the tubular rollers and swaging the tubular roller end around the outer surface of the bearing casings. The swaging deforms not only the ends of the tubular rollers but also the outer casings of the bearings, and such deformation tends to preload the bearings. This preloading may cause premature failure of the bearings. In addition, once the bearings are so swaged into place, they cannot be individually replaced, and accordingly, the entire roller-bearing assembly must be discarded if either bearing fails. Alternatively, outer cylindrical surfaces of the outer races, or complementary inner cylindrical surfaces of the ends of tubes, or both, may be carefully machined to produce interference fits.
Both prior art methods require expensive machining or crimping steps and make extraction and replacement of bearings difficult.
Welding of roller ends to bearings is not desired because it makes replacement of worn rollers or bearings difficult and because welding may injure bearings or rollers or may require unusual and more expensive greasing packing sequences.
In all cases, it is highly desirable to be able to replace an repair rollers and bearings and interfit rollers and bearings in the field as quickly as possible with minimal conveyor down time. Because of the great numbers of rollers and bearings in each conveyor, it is desirable to use inexpensive non-machined parts which do not require holding to close tolerances.